Drive mechanism for sewing machines



Jan. 12, 1960 M sHAPlRo 2,920,7301

DRIVE MECHANISM FOR SEWING MACHINES E l FIG. l. l? v ya; 93 l al v 89 I www INVENTOR MORDECAI SHAPIRO.

BY 771:2(1'454l Mm.

ATTORNEYS.

Jan. 12, 1960 M, sHAPlRO 2,920,730

DRIVE MECHANISM FOR SEWING MACHINES Filed Sept. 6, 1956 3 Sheets-Sheet 2 INVENTOR MORDECAI SHAPIRO.

ATTQRNEYS.

Jan. 12,` 1960 M. sHAPlRo DRIVE -MECHANISM FOR SEWING MACHINES 3 Sheets-Sheet 3 Filed Sept. 6, 1956 |NvEN-ron MoRDEcAl sHAP/Ro.

ATTORNEYS.

United Seres Patent,

e l2,920,730 DRIVE MECHANISM FOR SEWING MACHINES Mordecai Shapiro', Merrick, N.Y., assignor to National Safety Table Company, Merrick, Long Island, N.Y.

My inventionrelates to a new and improved drive mechanism for driving various machines, such as sewing machines.

It is well known to provide a drive mechanism which has a longitudinal motor. shaft or power shaft; a longitudinal driven shaft or transmission shaft; to provide for a. relative longitudinal movement between said shafts, and to provide said shafts with dry friction clutch members which are coupled or uncoupled by the relative longitudinal movement betweensaid shafts.

Such dry friction clutch coupling between said shafts, according to prior practice, has resulted in irregular and jerky coupling and operation, especially when the motor shaft or power shaft'and the ldriven shaft were rotated at high speed, such as 3,600 revolutions per minute, `which is the usual speed of a motor shaft or power shaft in a transmission for a sewing machine. In such high- Vspeed rotation, it has been necessary to provide dynamic and static balance` for the motor shaft, and also for the driven shaft. The usual dry friction clutch wears fairly rapidly, which results in a jerky drive, thus injuring `the sensitive parts of a sewing machine, and resulting inv objectionable noise. l Y.

According to, one feature of my invention, I provide one of said shaftsV with a rigid and dry friction block, which preferably and optionally has anV annular friction face `which is'concentric with the common longitudinal Aaxis of both the motor shaft and the driven shaft.

block may be made of any suitable friction material,

.such as the material which isused to make rigid brake blocks. The well-known rigid VRaybestos lillustrates such material. Such rigid friction material usually includes asbestos powder or 'asbestos fiber, an asbestos cement, and other ingredients, such as silica sand, coke Due to their resilience, said metal plates have selected normal shapes, to which they return after being flexed. Without limitation thereto, said normal shapes may be flat, disc shapes. Thefaces ofzsaid metal plates may be fairly smooth, but said metal plates have a sufficient high friction to act as friction coupling members. The `central parts of said plates are provided with intermediate spacers, which may be ilat, rigid metal discs. The central parts of said plates and said spacers arexed rigidly to the respectiveshaft, either the motor shaft or the driven shaft, so that said plates and spacers rotate in accurate unison with the respective shaft.

By means Iof these spacers, saidY plates are provided with outer peripheral zones, or portions, which are freely .flexibleandresilient in. a sliretiqnparallel .to thegaxis of 2,920,730 Patented Jan. 12, 1960 the` shaft to which said plates are fixed. These outer peripheral portions may be of annular shape.

These outer peripheral zones or portions are axially alined with the annular friction face of the rigid friction block. Said outer peripheral Zones or portions preferably extend radially inwardly of the annular friction face ofthe rigid friction block.

The metal plate which directly contacts with the annular friction face of the rigid friction block, when the clutch is coupled, is preferably made of brass. The other metal plate or plates can be made of aluminum or aluminum alloy or'other suitable material.

' The clutch can` be coupled by longitudinally shifting Vthe driven shaft towards the motor shaft.

If the rigid friction block is connected to the motor shaft, this results in bending or ilexing said resilient and flexible -outer peripheral zones axially away from the annular friction face of the friction block. When the clutch is fully coupled, one of-said bent outer peripheral zones yis in Vfrictional contact with the annular face of therigid friction block, and all of said axially bent 'outer peripheral zones are in frictional contact with each `other at their adjacent facesthus distributing the fricvtionaldriving force over all the outer peripheral zones.

If 'the flexible metal plates are connected to the motor shaft, they are providedwith a rigid abutment which is lixedto said'motor shaft. The flexible metal plates are `located vintermediate said rigid abutment and the rigid frictionblock'which is iixed to the driven shaft in this case. In'such case, the flexible outer peripheral zones a're bentl andlo'ngitudinally clamped betweenl said rigid abutment and the annular friction face of the rigid block, when the clutch is coupled, and the adjacent faces of thesaid outer peripheral zones are then in frictional contact. This also distributes the. driving force over all the outer peripheral zones.A y

Depending uponi the driving force, the transmission ymay'have two or three or more flexible metal plates.

It is thus possible to provide a dry clutch which has a plurality of thin metal plates, upon which the frictional driving force is distributed. I can thus use thin, resilient and flexible metal plates or metal members of normal ,llat shape or of other normal shapes. Thus, if I used only a Vsingle metal plate of the low thickness later mentioned herein, such single metal plate would not provide the required friction, and it would be bent permanently out of normal shape by the driving force, if such single metal plate efficiently transmitted the entire vdriving force.

The selection of metals and the finish of their surfaces, in order to transmit a frictional force, is well known. These factors are described, as one example, in the 1941 edition of Mechanical Engineers Handbook, published by McGraw-Hill Book Company, Inc.

I also provide a rigid brake block, which may be made of friction material which has an annular contact face, or ,whichV may be made of any material and which has .an annular friction strip.

If the flexible plates are fixed to the driven shaft, the outer peripheral zone of one of said plates contacts with the :fixed 4and rigid brake at the end of the uncoupling stroke of the driven shaft. At the end of said uncoupling stroke, all the outer peripheral zones are bent axially away from the fixed and rigid brake, and the adjacent faces of said outer peripheral zones are then in frictional braking contact. This distributes the braking force over all the peripheral zones.

If the flexible metal plates are fixed to the motor shaft, and the rigid 'clutch block Vis fixed to the driven shaft, said .rigid clutch block is in braking contact with the lixed andYrigid brake at the end of the uncoupling stroke Ofthadriven shaft.

Whenever I refer to longitudinally shifting the driven shaft relative to the power shaft or motor shaft, I include any relative coupling or uncoupling movement between said shafts, and I also includeany relative cou,- pling orv uncoupling movement between the respective clutch members, if the shafts are not longitudinally shifted.

I alsoprovide improved means for llongitudinally shifting the brake'in various respective 'lixedvpositions I also provide an improved adjustment for a spring which automatically uncouples the clutch and applies the braking force, when the clutching force is released by the operator.

I also provide an assembled casing, in lwhich all `the parts of the transmission are located, said assembled c asing .being turnable about va longitudinal axis by gravity Yor by applied force, in order to .apply sufficient tension commencement of the braking action.

`Fig. 4 is a section similar to Fig. 3, showing the clutch iust before the commencement of the coupling action.

When the clutch is finally coupled, the peripheral, spaced parts of the flexible and resilient metal vplates are pressed against each other and are bent longitudinally towards theannular face of the rigid friction member, as illustrated in Fig. '8.

Fig. 5 is a transverse section on the line -5-'5 lof Fig. l.

of housing 22. Said threaded shank of clamping screw 29 is easily movable in the slot 27a of the bar 27. Hence, when the head of clamping screw 29 is spaced from bar 27 and said screw is in loose position, the housing 22 can be turned laterally in either direction around the longitudinal horizontal axis of pivots 1S and 19, while the threaded -shank of clamping screw 29 engages the thread of the recess of the wall of housing 22. When housing V22 is -thus Vlaterally turned or pivoted .around .the common, longitudinal and horizontal axis of pivots i1@ and `19, the threaded yshank-.of clamping screw y29 slides or moves easily in the slot 27a of bar 27. This slot 27a may fbefclosed `at -bothends thereof, in'order to limit the sliding movement of the threaded shank of clamping screw '29.

The clamping screw 29 may be adjusted to its loose position so that its head is spaced from bar 27', in which case gravity biases the housing 22 to its bottom position. When'housing 22Yis in its bottom position, the bars or rods`23' and 24 are vertical.

If desired, the housing 22 can be laterally turned or pivoted around the common axis of ,pivots 18 and 19 to any selected lateral position, in which bars 23 and 24 are 'inclined to the vertical direction and the clamping screw 29 can then be turned until its head clamps against `the 'bar'2'7, in order to maintain housing 22 in its laterally turned position. Said casing or housing 22 is fixed rigidly .to anassoeiated longitudinal casing .or housing 33.

n' :Said housings '22 and 33 'are an assembled housing.

Fig. 6 is a longitudinal sectional view which illustrates theksecond embodiment, which has a modified driven shaft which can be used either in the rst or third embodiments. Y

Fig. 7 Vis a longitudinal sectional view .of the .preferred third embodiment, 'in which the metal plates are -xed to the motor shaft or power shaft. It shows .the clutch in uncoupled and lbraked position.

Fig. 8 is similar to Fig. 7 showing the clutch in yits coupled position, in which the ilexible yand resilient ,peripheral parts of the inetal Vplates are pressed against each other by the peripheral parts of a rigid member fixed to the motor shaft and of a rigid, friction clutch member fixed to the driven shaft.

Fig. 9 isa transverse elevation on the line 9--9 of Fig. l7.

First embodiment-Figs. 1-5

The ,rigid bracket 11 has an integral top plate 114. Said rigid plate 14 vis fixed by bolts 15 to the table 12 of a sewing machine. .Said rigid plate 14 .is integral with rigid, vertical :arms 16 Vand 17. Rods or .bars 23 and 24 are respectively pivoted 2to Aarms 16 Vand 17, by respective longitudinal and horizontal pivots 18' and 19, whose 4longitudinal axes are .on the same longitudinal, horizontal line.

Another rigid arm or bar "27 is pivoted toarm 17 by a longitudinal and horizontal pivot 28, whose longitudinal axis is above .the common tlongitudinal horizontal axis of pivots 18 and 19.

Said arm 27 has a'vertieal slot 27a.

Said pivoted rods or bars .23 are fixed to a longitudinal casing or housing 22 by respective bolts 23 and 124, fso that longitudinal housing 22 is laterally turnable about the `common longitudinal axis of pivots 18 and 19.

A clamping screw 29 has a threaded shank which extends through slot 27a .of rod 271. Said threaded shank of screw 29 engages the thread of a recess in the `wal-1 For Ythis purpose, the housings 22 and 33 are provided withrespective circumferential, Vannular flanges .22a and 33a, which'have .pairs of adjacent longitudinal bores, as illustrated `Yby the 'longitudinal bores B of flange 33a in Fig. 3. These bores yB are arranged in longitudinally alined pairs, through which clamping 'bolts 34 pass, in order to clamp housings ,'22 and 33 .rigidly to each other, so that they are turnable in .unison around pivots 13 and T19, asa Ysingle assembled housing.

A motor, such as an electric motor, is located within yand iixed to housing 22. This motor -is not shown, as it is conventional. Fig. 1 shows the flexible cable 31, which .supplies .electricity to the electric motor. This .motor has a longitudinal motor shaft 32. The shaft 32 lmay be driven in any manner. It has suitable bearings in housing .22.

j As shown in Figs. 3 and 4, a collar 42 is releasably .xed to .motor shaft 32 by one or .more clamping screws `43.

Said motor shaft 32. extends through the central bore of a rigid clutch block or clutch member 41, which is made V of any suitable rigid, friction material, such as Raybestos This clutch member 41 has an annular recess 46, which is concentric with shaft 32, and an annular, Vfrictional engaging face P which is also concentric with shaft 32. Said friction clutch member 41 is iixed to collar 42 by longitudinal, releasable screws 45.

As shown in Fig. 3, said clutch block or member 41 is located within the housing or casing 33.

This motor shaft 32 is accurately alined with a longitudin'al driven shaft 49, which extends beyond one end of the housing or vcasing 33.

'Said -driven shaft 49 is .longitudinally shiftable relative to housing 33.

For this purpose, said housing '33 is provided with an internal, integral, guide 37, whose inner and outer walls have the shape of respective longitudinal cylinders which are concentric with lthe common longitudinal axis of driven shaft '49 and motor shaft 32.

An inner, cylindrical and longitudinally shiftable sleeve 54 has an outer cylindrical wall which tits accurately and slidably and turnably against the inner cylindrical wall of guide 37.

This 'slidable and cylindrical sleeve 54 is part of a bearfingr`5-1 for the driven shaft 49.

As shown in Fig. 3., said driven shaft 49 has an interapparso inediate or median cylindrical section KSt), and reduced, cylindrical inner and outer end-sections 52 and 53.

As also shown in Fig. 3, the inner 'cylindrical face of the slidable sleeve 54 has transverse, continuous circumferential grooves 57. Anti-friction balls 55 iit partially in said grooves 56 and 57, so that motor shaft 32 and driven shaft 49 are maintained in accurate longitudinal alinement, with a common horizontal and longitudinal axis of rotation.

By means of these anti-friction yballs 55, the sleeve 54 and the driven shaft 49 can be accurately longitudinally shifted in unison, and the driven shaft 49 is also provided with an anti-friction bearing relative to sleeve 54, which may have little or no turning movement relative to guide 37 of casing 33.

A longitudinal collar 63 is rigidly xed to the inner end-section 52 of driven shaft 49, as by a press t or in any suitable manner.

' The reference numeral 64 indicates a group of thin, flexible and resilient metal plates 65, 66, 67. The invention is not limited to the use of three plates. Each said plate 65, 66, 67 has a central perforation. Respective spacers S are located between plates 65-66 andbetween plates 66-67. Each said spacer S also has a central perforation. s

These spacers S may be rigid and identical.

Without limitation to the specific details stated herein, certain dimensions and details are stated, as one practical working example, for transmitting horsepower, when shafts 32 and 49 are rotated at 3600 revolutions per minute.

Said plates 65, 66, 67 have an outer diameter of four inches, and an inner diameter of 5%; inch. The spacers S, which may ybe rigid, have an outer diameter of two inches, and the same inner diameter as plates 65, 66, 67.

The annular face P of the rigid frictional block 41 has an outer diameter of four inches and an inner diameter of inch. l

The collar 63, which is later more fully described, has an outer diameter of 11/2 inch, and a planar face adjacent place 67.

The thickness of spacers S is .010 inch.

Plate 65 is made of brass, with a thickness of .032 inch.

Plate 66 is made of aluminum or aluminum alloy, with a thickness of .032 inch.

Plate 67 is made of aluminum or aluminum alloy, with a thickness of .094 inch.

These flexible and resilient plates 65, 66, 67 have fairly smooth surfaces, but they have a sufficient coefficient of friction to uniformly distribute the driving force and braking force. f ,Y

The plate 65, which directly abuts face P, is preferably made of brass, which may have a lower coelcient of friction than'p-lates 66 and 67. Said plates 66 and 67 can also be made of brass, but aluminum or aluminum alloy or other suitable metal may be used.

The collar 63 is xed rigidly to the section 52 of driven shaft 49, as by a press fit or other means. Said section 52 ts closely in the central perforations of plates 65, 66, 67 and of spacers S.

Longitudinal clamping screws 68, which extend through and fit in bores of plates 65, 66, 67 and spacers S, rigid ly fix and clamp the central parts of the rigid spacers S and the central parts of plates 65, 66, 67 to collar 63, so that said spacers and plates rotate in accurate unison with driven shaft 49.

The outer, annular, peripheral parts of plates 65, 66, 67, which extend radially beyond s'pacers S, are free to flex. Due to their resilience, said outer parts of plates 65, 66, 67 return to their selected normal shape when the flexing force is released. In this illustration, said plates 65, 66, 67 have normal, flat disc shapes, but they may have any normal shapes, as long as they. provide and distribute the necessary frictional coupling and braking force.

.of integral lugs 36a.

4with and to ilex the peripheral part of plate 67 to the right. In their flexedv or bent` form, the outer portions of plates 65, 66, 67 have truste-conical shapes, and their adjacent faces are iny frictional contact. l

As shown in Fig. 3, a rigid collar 61 is rigidly xed to the outer reduced section 53 of transmission shaft 49, as by a press t or in any suitable manner. The halves of a conventional split pulley 62 are fixed rigidly to said `collar 61 by longitudinal screws 61a.

In using the mechanism illustrated herein, said split pulley 6 2 is connected by a ,conventional endless belt, not shown, to the conventional driving pulley of the sewing machine or other machine. This machine and its pulley are not shown, as `they are conventional.

A protective cover for said belt has a top and side opening 76, through whose top said drive belt extends upwardly to the pulley of the sewing machine or other machine. A Y r This cover 75 is pivotally connected to casing 33.

, As shown in Fig. 2, casing 33 is provided with a pair Said cover 75 is pivotally connected to one of said lugs 36a by a horizontal and longitudinal pivot pin 77b. Figs.- 1-3show the latched position of cover 75, in which it is releasably held by a removable and longitudinal latch pin 77, =which extends through a bore of cover 75 and through a bore of the respective lug 36a of casing 33.

As shown in Fig. l, a compression spring 77a is located around the shank of latch pin- 77. One end of `spring 77a abuts cover 75; The` other end of spring 77a is connected to the shank of latch pin 77, so that latch pin 77 is biased to the latching position of Fig. 1 by spring 77a.

When latch pin 77 isl pulled longitudinally outwardly from said latching position, it is pulled out of the bore of the respective lug 36a, so that cover 75 can turn downwardly about the horizontal axis of pivot pin 77b to an open position, in which the belt can be easily applied to or removed from pulley 62.y When latch pin 77 is thus pulled out of its latching position, it remains assembled with cover 75, and it turns with cover 75 around pivot 77b.

When a drive belt is -to be installed, or removed and replaced, the cover 7S is released from casing 33, and said cover 75 is turned downwardly around pivot 77 from its latched position of Figs. l-3. At this time, the clamping screw 29 is in its loose position. The operator turns the connected casings 22 and 33 towards him, around the axis of pivot pins 18 and 19, as indicated by the arrow A inFig. 2.

The endless belt can then be easily placed upon pulley 62 and upon the associated drive pulley of the sewing machine or other machine. The operator then releases the connected casings 22 and 23, which turn by gravity in a direction reverse to arrow A. When the belt is thus installed, the released casings 22 and 23 thus turn by gravity to a position in which rods 23 and 24 remain forwardly inclined from vertical position, so that the weight ,of casings 22 and 33 and of the parts therein, may impose suitable driving tension upon the drive belt. If greater tension on Ythe drive belt is desired, the operator additionally turns the connected casings 22 and 23 away from him, in a direction reverse to arrow A, until the tension on the drive belt is suitably increased,`and he then tightens clamping screw 29, in order to clamp-the ,connected casings 22 and 33 in their adjusted position. That is, the length of the endless belt is less than the vertical distance between the pulley of the sewngrma-t depending 4vertical position.

chine vand thepulley=62,\when'rods 23 and 24 are in -After the 'tension on the Ydrive'belty has beenthns selected,-the coverk`75 is turned to its latchingposition, andthe assembled 'latching-pin 77 `is moved to 4its latching rpositionby rspring 77a.

As vshownin Fig. -3, `a rigid'brake block 70 fits closely Vand slidably upon the outer cylindrical lface `of the cylindrical guide 37. `I1`his--rig`idfbrake block'70 is'provided in this embodiment -with an annular friction `strip '72, which -is made of suitable Vfriction material, rand which is fixed to said brakeblock "70.

AsshowninlFig. land Tig. 5, the housing 33 has a slot "40 which'isinclinedtothe common longitudinal axis of 'the transmission-shaft"49 and motor'shaft 32. 1 he clamping vscrew 71 has athreaded shank vvhich'extends slidably through said"`slot"40. HThisthreaded shank of clamping screw 71engages the thread of arecess of brake block '70. `Wi1en"clarnpingscrew '7l-is loosened, without disengaging it frombrake block 70, the'threaded shank of said Vclamping vscrew 71 can lbe shifted yin slot 40, thus 'turning brake block 70` around a -longitudinal axis, and-also longitudinally shiftingbrakeblock `-70 to a selected adjusted'longitudinal position irelative'tothe plate 67 'of the gronp64. Thecla'mpingescrew 71-is then tightened, in order to clamp brake block '70 in'its adjusted longitudinal `position.

Hence, whenthedriven shaft '49`anditsllexible plates are moved in unison, longitudinally Vaway from vmotor shaft 32, the 'outer face of the plate'67 of group'64'contacts with the friction `strip 72, which is Sfixed Vto :the fixed brake block 70, 'thus orakingthe drivenshaft 49. "When the driven -shaft 49 is in'nal'brakingposition, the outer, flexibleiparts of all `the kplates ofgroup 64 are exed `and contact witheach other, 'to provide a braking effect, and saidouterparts'thenhave'frusto-conical shapes and they frictionallyabut each other.

Fig. t3 -shows'the'position of plates `65, 66,67, just when the 'braking action begins.

As the brake strip 7-2 Wears,the`longitudinal adjustment of the brake Amember 70 can also be regulated in order to compensate for -wear. Thus, -if screw 71 is shifted frornits position oflFigfl, the'brake'70 is longitudinally'shifted tothe left, tocompensate for wear of strip .72.

AsshownzinjFig. 3,"the sleeve' 54`has a vertical opening 59 and'the'tubular guide 37 .has a 4larger vertical opening '39, andthe casing33lhas a corresponding land stillla'rgervertical opening. A ro'd 82 is pivoted at'83 to a lug of a casing 33. This rod SZextends through the opening '139 'of`thesleeve 37. 'Said rod SZ'has a head 82a which fits'fairly" closely in the opening '59 of the shiftable sleeve 54. Said rodSZ/hasan angularlever extension S50-S1, which is connectedby a'link`93 to a'pivoted operating treadle-92- When the'bar or rod 82 is turned infthe direction of arrow 9 of'Fig. 3, the head V82a longitudinally shifts vthesleeve 54 YVand therefore simultaneously shifts'the shaft-'49' so Yas to'move the group of discs 16S, '66, -6-/', to :the 'final i' coupling position.

A-spring Eis,providedlier-automatically returning the driven-shaft-49fto the-position shown in Pig. 3, when the pedal A92=is released, :andforapplying the'braking force. 'AsillustratedinFig 31, a-lug SS-is fixed tothe flange 33a.of the easing 33. A'Thethreaded end of a pin 86 is fixed ftosaid lug=8-8. Saidpin -86 extends through the bore of a hollow collar-93a of the lever 80. A washer y 9317 is 'mounted-uponasmooth part of; pin 86. A compression spring 89 is -moun-ted on-'the smooth part of pin .'S. Said 'spring Scan be held in a desiredcompressed-.position by means'of afcap'87 which is'threaded on the respective 'threaded vend of pin 86. As viewed in Fig. 4l, this compression spring '89 exerts pressure which'lbiases the lever-extension 80-81 to turn counterclockwise around pivot -83,thus automatically longitudinal'lyshifting the 4sleeve :S4-and driven shaft 49to the uncoupledposition of Fig. 13. The lexposed locationof 8 the cap 87 -andspring-'89-makes it possible very easily and efficiently to adjust the compression of the return biasing spring 89`in order-to suit the convenience-of the individual operator, and tolselect the brakingforce.

Second .embodiment-.F ig. 6

Iniths `embodiment,lthe driven shaft 95, whichvmay be'either'hollow `or-solid, takeslthe place of the driven or transmission shaft 49, or the driven shaft of the'third embodiment. rI'his=driven'shaft '95 lowers the cost of manufacture andlfacilitates assembly. This driven shaft `has reducedl end-portions -97b and"98b. VTheplatesof the group f6ltscan-be mounted 'and clamped to the end portion 97h, and thescrewsf68-of the first embodiment can be screwed into the tapped longitudinal recesses of the section 97vof the .drivenshaft 95. VThe pulley-62 canibe fixed to the section/98b, by means of said vscrews 61a, which enter the tapped recessesof section 98. The bearing 51freplacesfthe'bearing A5f1-of the first embodiment and the sleeve 54 takes the place of sleeve`54'of theiir-stembodiment. This sleeve 54 is slidable within -andturnable relative to the yguide`37 of the-first embodiment. VVTheanti-friction balls 55 have the same function ias'the balls 55.

Third embodiment 11n this embodiment, "arigid collar 42 `is -fixed to motor-shaft`3'2". -For ythis purpose, collar 42 may Vhave one'or'moreflatfextensions or'keysv 42a, which fit closely inlongitudinal 'recesses of motor shaft V32". Conventional clamping screws can be used for rigidly fixing collar-'42 to motor 'shaft '132".

In this example, a Aflat,'rigid abutment plate y102, two lexibleplates L100 and*-101, land two rigid spacers 103 and 104 are rigidly clamped to collar '42"'by longitudinal clamping-'screws*105, which operate like the clamping screwsiS. Y"Ihese'plates102,100, 10.1*provide a group 41".

In thisl example, the :at'and rigid abutment disc/102, which may optionally be somewhat bendable and 'resilient, is made of aluminum or aluminum alloy, with a thickness of 0.092 inch. In this example-the resilient and flexible-plate 100" is made of aluminum, with a thickness of 0.033 inch. AIn this example, the resilient and flexible plate 101 is made of brass, with a thickness of 0.038 inch. IkSaid'perforated plates 1102, 100, 101'have outer diameters of4 inches, and-inner Adiameters of Sys inch. The rigid, disc-shaped spacers 103 and 104 are made of stel,'withan youter diameter of 2 inches. The plates `1'02,100,"1011and the spacers '103 and 104have respective central perforations, which fit closely onmotor 'shaft 32". The thickness'of `spacers 4103 and 104 is .G10-inch.

In this embodiment, the flexible and resilient plates 100 and -101 have normal flat disc-shapes,'but'the invention is not limited to said normal shapes.

Fig. V8 shows the exed shapes of the peripheral parts of plates 100 and 101, when the clutch is fully coupled. Thev peripheral friction parts of plates 102, 100, 101 are also fairly smooth. As shown in Fig. 8, the peripheral parts 'of plates 2100'and 101 are `clamped between rigid plate 102 and the rigidfriction block 64".

The driven shaft `49'falso has reduced end-portions. The Ishiftlever 80 operates as in the first embodiment, in order to shift the longitudinally shiftable sleeve 54a, which corresponds to sleeve 54 of the first embodiment. The internal bball-bearing of the firstembodiment is used in this third embodiment.

yA vcollar 106 is-rigidly xed to section 49" of driven shaft 49.

The vdriven and rigidfriction clutch block 64", which can also be made of "Raybestos is Vfixed to collar 106 by-longitudinal screws 110. rThis driven clutch vblock e4 also'has'aeentral'recess,which is concentric with the common axis of shafts 32 and 49.

In this embodiment, the rigid clutch block 64" is pressed against the annular face of brake block 70a in the braking position.

I claim: 1

1. A power transmitter which comprises a support and a casing, a longitudinal motor shaft and a longitudinal driven shaft supported in bearings in said casing, said shafts having a common longitudinal axis, one of said shafts being longitudinally shiftable relative to the other shaft, a rigid friction clutch-member block xed to one of said shafts, said block having an annular friction face, the other shaft having a plurality of axially spaced flexible plates fixed thereto, adjacent plates having rigid spacers of smaller radius than said annular friction face with flexible peripheral zones, said peripheral zones being longitudinally alined with said annular friction face, the shiftable shaft being shiftable towards the other shaft to a coupling position in whichy said friction face contacts with the peripheral zone of the next-adjacent flexible plate and all said adjacent peripheral zones contact frictionally with each other.

2. A power transmitter according to claim 1, in which said friction face is annular and at the outer periphery of said rigid friction block, and said block has a longitudinal recess radially inwardly of said annular friction face, the central parts of said plates being located in said recess in said coupling position.

3. A power transmitter which comprises a casing adaptable for mounting on the end of a motor having a drive shaft extending therefrom, said casing having an exterior end wall with an inwardly projecting bearing sleeve, an axially slidable bearing in said bearing sleeve, a driven shaft rotatably mounted in said slidable bearing in alignment with said drive shaft, friction clutch means between said shafts operated by sliding said slidable bearing and driven shaft toward said drive shaft, said clutch means comprising annular axially opposed friction members on the adjacent ends of said shafts, a third annular friction member slidably adjustable on said bearing sleeve for cooperation with the outer face of the annular friction member on said driven shaft to provide a brake when the driven shaft is moved away from said drive shaft, one of said axially opposed annular friction members being comprised of a plurality of aligned plates carried by one of said shafts, and spacers between said plates, said plates having flexible peripheral portions to provide successively greater friction between said friction members as additional portions are brought into mutual contact by continued movement of said driven shaft toward said drive shaft with increasing pressure until the peripheral portions of all the plates are pressed together.

4. A power transmitter according to claim 1 wherein the plates are xed to the motor shaft and the driven shaft carries said friction clutch-member block, said flexiole plates being located longitudinally between said rigid clutch-member block and said friction face, said peripheral zones of said plates being clamped between said rigid clutch-member block and said friction face in coupling position.

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